1. Field of the Invention
The invention relates to a method for reducing motion blur of images shown in display devices, in particular, resulting from integration by the viewer of pixel intensities along the motion trajectory, which can be interpreted as a low-pass filtering in the spatial domain, due to motion-dependant spatial low-pass filtering on image data along a motion trajectory, in which motion vectors depending on moving components of an input video signal are calculated, filter coefficients depending on said motion vectors are calculated, said input video signal is filtered depending on said filter coefficients providing a filtered video signal, an output video signal is generated by combining said input video signal and said filtered video signal, and images are generated on said display device depending on said output video signal. The invention further relates to a circuit arrangement providing anti-motion blur function and a non-stroboscopic display device. Said motion-dependant spatial low-pass filtering might as well be caused by the display itself.
The invention provides a favorable dynamic behavior of non-stroboscopic display devices, such as, Liquid Crystal Displays, Plasma Panel Display or Color Sequential Displays.
2. Description of the Related Art
European Patent Application No. EP 0 657 860 A2 discloses that motion blur in non-stroboscopic displays can be reduced by filtering an input video signal. The filtering is carried out as a speed-dependant high spatial frequency enhancement. As the viewer of moving objects on a matrix display integrates the intensity of the pixels along the motion trajectory, which corresponds to a low-pass filtering in the spatial frequency domain, motion blur may be reduced by filtering the high spatial frequency of moving objects. According to this document, matrix video display systems for displaying moving images comprise a matrix display panel having a row and column array of picture elements for producing display outputs, and a picture element drive circuit for driving the picture elements according to a video signal applied to an input by addressing the rows of picture elements in sequence repetitively in successive fields, with the picture elements holding their display outputs for at least a substantial part of the interval between successive addressing. These matrix display devices are non-stroboscopic displays. To reduce motion blur, it is proposed that a speed-dependant high spatial frequency enhancement filter circuit is provided, via which video information of a video signal applied to said input is supplied to the picture element drive circuit and which enhances the spatial frequencies of moving components in the image to be displayed according to the speed of the moving components. The higher the speed of the moving components, the larger the part of the spectrum that needs enhancement.
A drawback of the proposed solution is that in areas where the motion vector is not reliable, i.e., in areas where there is little contrast, filtering may be carried out without improving the picture. Furthermore, this filtering may even cause noise modulation. In such a case, flat parts of the picture are filtered where filtering cannot improve significant detail. It can, however, result in visible differences in noise patterns.